Re: [PATCH net-next] net: netconsole: Add continuation line prefix to userdata messages

Florian Fainelli <f.fainelli@xxxxxxxxx> · Wed, 28 Feb 2024 09:32:19 -0800

On 2/28/24 09:29, Matthew Wood wrote:
Add a space (' ') prefix to every userdata line to match docs for
dev-kmsg. To account for this extra character in each userdata entry,
reduce userdata entry names (directory name) from 54 characters to 53.

According to the dev-kmsg docs, a space is used for subsequent lines to
mark them as continuation lines.

A line starting with ' ', is a continuation line, adding
key/value pairs to the log message, which provide the machine
readable context of the message, for reliable processing in
userspace.

Testing for this patch::

  cd /sys/kernel/config/netconsole && mkdir cmdline0
  cd cmdline0
  mkdir userdata/test && echo "hello" > userdata/test/value
  mkdir userdata/test2 && echo "hello2" > userdata/test2/value
  echo "message" > /dev/kmsg

Outputs::

  6.8.0-rc5-virtme,12,493,231373579,-;message
   test=hello
   test2=hello2

And I confirmed all testing works as expected from the original patchset

Fixes: df03f830d099 ("net: netconsole: cache userdata formatted string in netconsole_target")
Signed-off-by: Matthew Wood <thepacketgeek@xxxxxxxxx>
---
  Documentation/networking/netconsole.rst | 6 +++---
  drivers/net/netconsole.c                | 4 ++--
  2 files changed, 5 insertions(+), 5 deletions(-)

diff --git a/Documentation/networking/netconsole.rst b/Documentation/networking/netconsole.rst
index b28c525e5d1e..c2dec12f6060 100644
--- a/Documentation/networking/netconsole.rst
+++ b/Documentation/networking/netconsole.rst
@@ -197,8 +197,8 @@ Messages will now include this additional user data::
  Sends::
  
   12,607,22085407756,-;This is a message
- foo=bar
- qux=baz
+  foo=bar
+  qux=baz
  
  Preview the userdata that will be appended with::
  
@@ -218,7 +218,7 @@ The `qux` key is omitted since it has no value::
  
   echo "This is a message" > /dev/kmsg
   12,607,22085407756,-;This is a message
- foo=bar
+  foo=bar
  
  Delete `userdata` entries with `rmdir`::
  
diff --git a/drivers/net/netconsole.c b/drivers/net/netconsole.c
index 0de108a1c0c8..ffd3e19406b5 100644
--- a/drivers/net/netconsole.c
+++ b/drivers/net/netconsole.c
@@ -43,7 +43,7 @@ MODULE_DESCRIPTION("Console driver for network interfaces");
  MODULE_LICENSE("GPL");
  
  #define MAX_PARAM_LENGTH	256
-#define MAX_USERDATA_NAME_LENGTH	54
+#define MAX_USERDATA_NAME_LENGTH	53 /* 256 - 200 - 3 (for ' =\n' chars)*/

Could we take this opportunity to define MAX_USERDATA_NAME_LENGTH based 
upon MAX_PARAM_LENGTH - MAX_USERDATA_VALUE_LENGTH - 3 then?

  #define MAX_USERDATA_VALUE_LENGTH	200
  #define MAX_USERDATA_ENTRY_LENGTH	256
  #define MAX_USERDATA_ITEMS		16
@@ -671,7 +671,7 @@ static void update_userdata(struct netconsole_target *nt)
  		 * checked to not exceed MAX items with child_count above
  		 */
  		complete_idx += scnprintf(&nt->userdata_complete[complete_idx],
-					  MAX_USERDATA_ENTRY_LENGTH, "%s=%s\n",
+					  MAX_USERDATA_ENTRY_LENGTH, " %s=%s\n",
  					  item->ci_name, udm_item->value);
  	}
  	nt->userdata_length = strnlen(nt->userdata_complete,

--
Florian








